A way to estimate the amount of body weight that is fat and nonfat. Nonfat weight comes from bone, muscle, body water, organs, and other body tissues. BIA works by measuring how difficult it is for a harmless electrical current to move through the body. The more fat a person has, the harder it is for electricity to flow through the body. The less fat a person has, the easier it is for electricity to flow through the body. By measuring the flow of electricity, one can estimate body fat percent.